The present invention relates to a micromachining method for forming a three-dimensional microstruture minute structure and to a three-dimensional microstructure formed by the micromachining method.
A so-called micromachining for forming micromachines and other microstructures by using a micromachining technology is expected to be applied in various fields. As today's micromachining technology, a method in which a two-dimensional photolithography technology and an anisotropic etching technology are combined is mainly used to form a minute structure (or microstructure) of several micrometers to several millimeters. In addition, a technology in which a workpiece is cut by using a laser beam to form a two-dimensional structure is available. Also, a bonding technology is known in which bonding of silicon substrates to each other or a silicon substrate to a glass substrate etc. can be accomplished by using an anodic bonding technology.
The limitation in conventional two-dimensional micromachining technology is that even when a three-dimensional structure is formed by combining a plurality of pares, the three-dimensional height of structure is restricted by the thickness of the original substrate. This limitation constitutes an enormous obstacle in manufacturing a mobile structure, a three-dimensional sensor, and the like.
Further, the prior art has a disadvantage that in it is difficult to manufacture a multilayer structure. For the construction of the multilayer structure, a bonding technology used for substrates is available. However, the bonding of substrates requires heating or other processing, so that the bonding strength and the durability, which depend on the difference in coefficient of thermal expansion and the condition of bonded surface, are liable to be unreliable. Also, since a bonded surface of a given range is required, the area of the bonded surface on the substrate must be large with respect to the functional portion. Moreover, the bonding technology is unsuitable for assembling a complicated structure.